1. Field of the Invention
The present invention relates to apparatus for automatically providing bass rhythm accompaniment and chords in electronic musical instruments and, more particularly, to apparatus for storing the rhythm patterns as binary data and for retrieving the data and using it to drive a programmable pedal signal generator in response to the playing of a pedal in a first mode of operation, or in response to the playing of a key in a second mode of operation, and for providing in the second mode of operation automatic chord generator means.
2. Description of the Prior Art
Various types of automatic chord and automatic rhythm accompaniment devices for electronic organs are known in the prior art. One example is the automatic chord and rhythm system described in U.S. Pat. No. Re.29,144, reissued Mar. 1, 1977 to Bunger. The system described in '144--Bunger is capable of producing automatic rhythm patterns in both percussive and accompaniment voices, as well as automatic chords in accompaniment voices. In that system, a rhythm pulse generator and enable-disable logic controlled by sixteen rhythm select switches provides trigger pulses to enable accompaniment voices and percussive voices. The rhythm percussive voices are generated by gating on an oscillator or noise generator whenever a trigger pulse is received. Thus, the rhythm percussive voices are merely pulsed on by the rhythm pulse generator and the enable-disable logic with no provision being made for controlling the frequency of the rhythm percussive voices. The accompaniment voices in '144--Bunger are developed by chord selector logic so that when a key is depressed, note frequencies from a generator cause a chord signal to be applied to the inputs of accompaniment voide signal gates. The accompaniment voice signal gates are turned on whenever a trigger pulse is received from the enable-disable logic. Thus, rhythmic chords can be provided from the accompaniment voices.
Another patent describing an automatic chord and rhythm system for an electronic organ is U.S. Pat. No. 3,629,481, issued Dec. 21, 1971, also to Bunger. In that system, bass percussive voices are triggered simultaneously with bass notes (root or fifth) and other percussive voices are sounded concurrently with the chords. The chord attachment operates to provide rhythmic sounding of both the pedal and manual frequencies, and the rhythm feature provides five basic rhythms, which employ pedal tones alternating between the root and fifth notes. In an automatic chord mode of operation, the system described in '481 Bunger triggers percussive sounds by actuation of a keyswitch, whereas in an automatic rhythm mode of operation the percussive sounds are sounded repetitively irrespective of and independently of the operation of a keyswitch. The system described in '481--Bunger plays both rhythmic chords and continuous chords.
Unlike these prior art devices, which provided simple pedal alternations between the root and fifth, the present invention provides harmonically appropriate automatic bass rhythm sequences and chords which are more complex, less monotonous, and which differ audibly depending upon which rhythm is selected. U.S. Pat. No. 3,665,090, issued May 23, 1972 to Wangard, et al., also describes a device for automatically producing bass tone patterns based on a tonic note. The system in '090--Wangard, et al. includes a switching network actuated by electronically produced pulse patterns and by pedal switches actuated by the instrumentalist. The switching network involves a plurality of pedal gate circuits with each circuit having a plurality of individual pedal gates equal to the number of semitones in a musical octave. The switching network also includes a plurality of audio gates actuated by pulses from the pedal gates to pass tone generator signals to an output audio circuit. However, unlike '090--Wangard, et al. the present invention stores rhythm pattern information in registers in a memory and uses a logic circuit to manipulate the rhythm pattern information, thereby eliminating any switching arrangement such as that utilized in the '090--Wangard, et al. patent.
U.S. Pat. No. 3,688,009, issued Aug. 29, 1972, to Wangard is similar to '090--Wangard, et al., except that the former does not include a switching network having pedal gates, audio gates and the associated diode circuitry. Instead, the device described in '009--Wangard uses pulses to actuate a plurality of tone signal generator means such as oscillators which are set by associated circuitry and voltages to generate different frequencies to produce the desired pattern of tone signals which operate audio means for production of the tone pattern; in some other instances the pulses actuate multiple voltage means for a single tone signal generator to provide different voltages in a pattern which determines the tone signals fed to the audio means. Thus, in that device distinctive voltage magnitudes represent corresponding tonic notes and a related group of notes having a predetermined interval relationship.
Another patent that describes an automatic bass rhythm device for electronic organs is U.S. Pat. No. 3,708,604, entitled "Electronic Organ With Rhythmic Accompaniment and Bass," issued Jan. 2, 1973, to Hebeisen, et al. As in U.S. Pat. No. 3,629,481--Bunger, the pedal tones played by that automatic bass device consist of a first pedal tone, usually the key signature, and a second pedal tone, usually the fifth of the scale. The present invention is not limited to two bass tones or to the root and fifth pattern in the automatic bass rhythm patterns generated and is much more versatile and efficient, as will be described.